An Italian Windows site called "Windowsette" has published some purported secret Microsoft documents outlining some design and strategy plans for Windows 8. The Microsoft Kitchen blog has provided some analysis of the documents. The documents appear genuine, and there's lots of interesting information there.

Although there are a lot of decent free (as in beer) programs for windows, this App Store/repo needs big names to play along to be considered a success. Think Adobe, AV vendors, game studios etc. All these would need a payment system to distribute their software through this mechanism